Method for uniform chrome plating of a plurality of miniature parts



3,383,292 I'IY May 14, 1968 F. WIELAND ETAL METHOD FOR UNIFORM CHROME PLATING OF A PLURAL OF MINIATURE PARTS Filed Sept. 15, 1967 2 Sheets-Sheet l INVENTORS FRANZ WIELAND JACOB w. ZANSlTIS WWW ATTORNEYS y 4, 1968 F. WIELAND 'ETAL 3,383,292

METHOD FOR UNIFORM CHROME PLATING OF A PLURALITY OF MINIATURE PARTS Filed Sept. 15, 1967 2 Sheets-Sheet 2 INVENTORS FRANZ WIELAND JACOB W. ZANSITIS ATTORNEYS United States Patent Office 3,383,292 METHOD FOR UNIFORM CHROME PLATING OF A PLURALITY OF MINIATURE PARTS Franz Wieland, Bethlehem, and Jacob W. Zansitis, Easton,

Pa., assignors to Rapidograph, Inc., Bloomsburg, N.J.,

a corporation of New Jersey Filed Sept. 15, 1967, Ser. No. 667,898 Claims. (Cl. 204-15) ABSTRACT OF THE DISCLOSURE Method of chrome plating a plurality of miniature parts, particularly chrome plating the leading edges of stainless steel and like stylographic drafting pen metallic points having miniature diameters in the range .009.051 of an inch, wherein the leading edges of the points are supported as an endless periphery of equally spaced contact points defined as a cathode within a chrome plating bath and an annular anode is positioned in the bath opposite the cathode, so that the leading edges of the points are presented nearest to the anode.

CROSS-REFERENCES TO RELATED APPLICATIONS Method for Assembling Miniature Tubing (Ser. No. 661,372, filed Aug. 17, 1967).

Method for Press Fitting Tungsten Carbide (Ser. No. 661,311, filed Aug. 17, 1967).

The earlier filed applications relate to the assembly of miniature points in stainless steel holders, the present application being directed to the chrome plating of metallic points.

BACKGROUND OF INVENTION Field of the invention In modern stylographic drafting instruments, tubular points, having diameters in the range .009.051 of an inch are manufactured from stainless steel, and like hard metals. These miniature points can then be chrome plated at their leading edges so as to provide a longevity factor. An essential characteristic of the chrome plating is that the plating shall be uniformly deposited about the leading, exterior edges of the point. If the plating is not uniform, the critical diameter of the miniature point is altered and, of course, there is inconsistency between the diameters of points within a particular size range. Also, the buildup of plating interiorly of the point affects ink flow, causing skipping or lines of varying width. Previously, electrolytic chrome plating of miniature parts has been exceptionally diflicult. The chrome has a proclivity towards heavier deposition at the corner or edges of the cathode with the result that points positioned at the cathode edge have received heavier chrome plating, while robbing interiorly positioned points of chrome. Various mechanical devices have been adapted to preclude heavier plating on those parts or points positioned at the edges or end of the cathode. One alternative was to mechanically rotate the cathode in front of the anode. However, the rotation of the cathode within the hot electrolytic bath has presented numerous mechanical diificulties and did not altogether solve the plating problem.

According to the present invention, the parts to be plated are supported in a circular path defined as a cathode which is positioned in the electrolytic bath co-axially with an annular anode, the anode is energized so as to create an electrolytic flow directly towards the parts to be plated. The parts to be plated being positioned equidistantly with their leading edges perpendicular to the anode, there is deposited a uniform plating on the lead- 3,383,292 Patented May 14, 1968 ing edge of each part. Consequently, the necessity for rotating the cathode is permanently eliminated.

Descriplion 0f the prior art Attempts at uniform plating were made by mechanical rotation of the cathode element about a fixed anode within the electrolytic bath. Also, shielding elements have been positioned in the electrolytic bath intermediate the anode elements and the object to be plated. However, none of the earlier inventors have attacked the problem of heavier plating on the corners or edges of the cathode by setting up a controlled electrolytic path.

SUMMARY OF THE INVENTION By supporting a plurality of parts, such as tubular stainless steel drafting pen points, to be plated within a circular path defined as a cathode within a plating bath and energizing an annular anode supported within said bath coaxially with said cathode, the energizing of the anode causes a controlled electrolytic flow directly onto the leading edges of the parts to be plated. Since the parts are equally spaced about the cathode and define an endless periphery of equally spaced contact points, the tendency for heavy coating on any one article is totally eliminated. Also, the elimination of sharp corners in the cathode and the elimination of the necessity for positioning of parts to be plated as an edge or end of a series totally eliminates the tendency of the chrome to be deposited as a heavier plating at any one point. Subsequently to plating, cleaning and etching of the parts may be accomplished by reverse current flow within a lye bath, then there may be rinsing and ultimate cleaning by ultrasonic vibration so as to remove dirt particles adhering to the plated articles.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view showing the co-axial alignment of annular anode and cathode, within a plating bath, the electrolytic path from anode to cathode being defined in phantom;

FIG. 2 is a perspective view of the front of the circular cathode, showing the miniature tubular drafting pen points to be plated extending vertically from the face of the cathode;

FIG. 3 is a side elevation with the stainless steel compression ring and nylon ring in exploded view and showing the V-groove holding slots in the metallic face of the cathode;

FIG. 4 is an enlarged vertical section of a tubular metallic point, showing in phantom the plating achieved on the leading edge by means of the present method.

DESCRIPTION OF THE PREFERRED EMBODIMENTS In FIG. 1 an annular anode generally designated as 10 is shown as being comprised of a lead alloy or like metallic ring exposed on its forward surface.

Cathode generally designated as 12 is illustrated in FIGS. 1, 2 and 3 as being comprised of supporting strut 20, plastic base plate 22, defining sealing ring ledge 38, and metallic front plate 32, having peripheral V-grooves 36 cut therein. Each V-groove 36 defines a slot for positioning of the pen point to be chrome plated. Metallic front plate 32 may be secured to base plate 22 by a plurality of 'bolts 28 and corresponding nuts 30.

Prior to plating, nylon or similar plastic band 44 is abutted against ledge 38 so as to be spaced apart from V-grooves 36. Then, the pen point tubes 26 are inserted in the V-grooves 36. Since the grooves are equidistant about the periphery, no one point is presented in an attitude where it may be subjected to heavier chrome plating. When the pen point tubes 26 are inserted in the V-grooves, stainless steel or like compression ring 24 is then clasped about the plastic band 44 by means of adjusting bolt 42 engageable with slots 40.

When the cathode assembly is completed as described, a cleaning and etching by reverse current may be effected-the rack cathode 12 serving as the anode Within a lye tank grounded as the cathode. The rack 12 is then energized to approximately 25 amps for several minutes. The cathode is then aligned within the chrome plating electrolytic bath co-axially with anode 10. The chrome bath may be comprised of CR of the type trademarked Unichrome SRHS-compounded and manufactured by M. & T. Chemicals, Inc. of Rahway, N.J., or a similar material. The bath may be pre-heated to approximately 130 F. The chrome plating may be effected by energizing the anode within a range of to 17 amps depending on the size (square inches) of the cathode. Normally, sufficient plating is completed Within to 20 minutes. Sequentially, rack 12 may be inserted in a chrome saving bath.

The chrome saving bath may be of the distilled water type, enabling recovery of chrome solution which may be poured back into the electrolytic bath. Subsequently, the rack is rinsed under hot water and subjected to a cleaning solution which may be heated. The cathode may then be disassembled by removing of compression ring 24 and plastic band 44. Points 26 may then be strain dried and subjected to an ultrasonic cleaner which removes the solution, as well as any dirt particles from inside of the points. The plated point 26 is then checked under a microscope, both as to diameter and possible flaking.

Manifestly, anode and cathode may be variously configured without departing from the spirit and scope of the claims.

We claim:

1. Method for uniform plating of a plurality of parts comprising:

(a) supporting a plurality of parts to be plated within a circular path as an endless periphery of equally spaced contact points defined as a cathode within a plating bath, the leading edges of said parts extending perpendicularly from said cathode;

(b) positioning an annular anode within said bath and opposite said circular path, so that the leading edges of said parts are presented nearest to said annular anode, the diameter of said circular path and the median diameter of said annular anode being substantially equal;

(c) energizing said anode so as to create an electrolytic fiow from said annular anode to the leading edges of said parts within said circular path.

2. Method for uniform plating of a plurality of parts comprising:

(a) supporting a plurality of parts to be plated Within a circular path as an endless periphery of equally spaced contact points defined as a cathode within a chrome plating bath, the leading edges of said parts extending perpendicularly from said cathode;

(b) positioning an annular anode within said bath and opposite said circular path, so that the leading edges of said parts are presented nearest to said annular anode, the diameter of said circular path and the median diameter of said annular anode being substantially equal;

(c) energizing said anode so as to create an electrolytic flow from said annular anode to the leading edges of said parts within said circular path.

3. Method for uniform chrome plating as in claim 2, said anode and said cathode being co-axially aligned and defining co-extcnsive circular paths.

4. Method for uniform chrome plating as in claim 2, including cleaning and etching said parts before plating by reverse current flow within a lye bath, by energizing said parts as an anode within said bath grounded as a cathode.

5. Method for uniform chrome plating as in claim 4, including final cleaning of said parts by ultrasonic vibration.

References Cited UNITED STATES PATENTS 1,733,608 10/1929 Knox et al. 204-9 2,438,885 4/1948 Bell 204-212 2,911,345 11/1959 Swenson 204-201 3,256,171 6/1966 Gualdieri et al. 204225 FOREIGN PATENTS 323,947 1/1930 Great Britain.

JOHN H. MACK, Primary Examiner.

HOWARD S. WILLIAMS, Examiner.

W. VAN SlSE, Assistant Examiner. 

